Monday’s heavy rains have nearly filled Lake Poway and water could soon spill over the concrete spillway designed to divert excess water into the canyons below.

City officials said Tuesday afternoon there is no immediate threat to life or property, but out of caution they have closed the Blue Sky Ecological Preserve and the hiking trails around the lake.

Later in the afternoon, Poway Mayor Steve Vaus said there is no cause to be worried.

“I’m not hearing any concern from our crews up here,” he said shortly after inspecting the dam. “It’s looking highly unlikely we will have to lose any water.”

Vaus said the rate the water level is rising has slowed considerably in the past few hours. At about 4 p.m. he said the lake was still about one foot below the spillway.

The spillway is a 100-foot wide span of concrete on the east side of the dam. It is designed to provide a safe route to divert excess water from the lake. Officials said city crews are working to lower the lake’s water level by diverting water to the city’s drinking water system.

The dam has been inspected and remains structurally sound, officials said.

If water flows over the spillway, it will enter the canyon north of the dam. The flow of water will be through the canyon, through parts of the Blue Sky preserve, under Old Coach Road, along Thomson Creek adjacent to Maderas Golf Course and ultimately into Lake Hodges.

Officials said the last time water flowed over the spillway was 1997. The overflow lasted one week and there were no reported injuries to people or damage to property.